There are various situations in which it is desirable to apply a chemical element or chemical compound in a relatively small, focused area according to a timed schedule or in dynamic response to particular conditions. In the medical field, for example, the timed or responsive release of medication or treatment such as the application of fluoride in dentistry is known to be beneficial. Periodic or responsive renewal of lubricants for micromechanical devices is another application in which the dispensation of relatively small amounts of selected compounds may be used to advantage. Returning to the example presented by the field of dentistry, oral biofilms are causative agents in many biological processes such as dental caries (cavities), periodontal disease and perio-implantitis. Dental biofilms contains a diverse species of microbes some of which have been identified as etiological agents for systemic diseases. The accumulation of dental biofilm can instigate a subsequent inflammatory and immune response. The control of dental biofilm is of paramount importance in managing periodontal disease and also plays a key role in disrupting the caries process. The human oral cavity has in excess of 700 different types of aerobic and anaerobic bacteria species. Biofilms are a complex community of microorganisms characterized by the excretion of a protective extracellular matrix, glycocalix, within which microbes are embedded. This matrix is adhesive in quality and allows for the attachment of microbe to microbe. The microbes in biofilms have a high rate of reproduction and are physiologically adaptive. As the microbes reproduce, they form complex, compound, interdependent colonies and the biofilms can achieve considerable thickness, up to 1 mm thickness within a four day period if undisturbed. Oral biofilms are initially colonized by gram-positive aerobic bacteria. As the biofilm becomes more mature and thickness increases, gram-negative anaerobic bacteria prevail and dominate. Infection with gram-negative anaerobes is associated with the release of bacterial toxins and proteolytic enzymes which are virulent, cytotoxic, or irritating to host tissues, resulting in host tissue injury and inflammation. The effect on the host is dependent upon the vulnerability of the host, the presence and prevalence of pathogenic bacteria as well as that of protective bacteria. In periodontal disease, relapse or refractory cases are intimately related to the presence of residual biofilm. Bacteria growing in biofilms have increased tolerance and resistance to antibiotics and antimicrobial agents, including those used in dentifrices and mouthwashes. The surface of the biofilm appears to be a physical barrier to the efficacy of chlorhexidine, inhibiting penetration or extinguishing it.
In spite of efforts to the contrary, dental Caries remains an endemic problem worldwide. Despite some modest decreases in tooth decay in the overall population, the incidence of decay remains high in specific subgroups. In particular, this includes individuals from low socioeconomic backgrounds and immigrant, ethnic minority populations. Cariogenic bacteria are passed on by caregivers (mothers) at a young age, the median age being 26 months. Early childhood caries affects one in six children. By the first grade, 50% of all children in the USA have had tooth decay. Early childhood caries appears to predispose children for decay throughout their lives. The implementation of water fluoridation has been extremely beneficial, but it is not without limitations. Although water fluoridation does affect the fluoride content of enamel during tooth development, the benefit of water fluoridation is primarily topical as opposed to intrinsic fluoride incorporation during tooth development. Fluoride reduces tooth decay by assisting in the prevention of demineralization and by remineralizing incipient lesions. Tooth decay is a process whereby demineralization, the mineral transfer from the tooth to the surrounding surface, is balanced or counteracted by remineralization. As a result, vast potential exists for improving and augmenting presently existing intervention techniques.
In the micromechanical field, lubrication in MEMs devices can be problematic. Traditional oils are generally not used because their molecules are too large in relation to the surfaces to be lubricated. Solid lubricants, such as various carbon compounds and monolayers of fluorocarbon materials may be used, but are susceptible to wear and are not self-renewing. Due to the foregoing and possibly additional problems, improved apparatus and methods for preventing tooth demineralization and promoting remineralization would be a useful contribution to the arts. In a broader sense, the electrochemical dispensing of targeted chemicals from chemical compounds would provide one or more advantages in diverse applications, such as in the medical and micromechanical fields.